1. Field of the Invention
The present invention relates to a method of sampling contaminants of a semiconductor wafer carrier, and more particularly to a method of sampling contaminants of a front opening unified pod (FOUP).
2. Description of the Prior Art
The diameter of semiconductor wafer is changing from eight inches to twelve inches because of the progress of the semiconductor industry and the consideration of economic effects. For conveying semiconductor wafers in an effort-saving, safe, and clean way, a front opening unified pod (FOUP) is used as a wafer carrier in the present foundry. The FOUP that is manipulateable and exchangeable is also used to store wafers temporarily for reducing the required area of clean room.
Referring to FIG. 1, it is a schematic diagram of a semiconductor wafer carrier 10. As shown in FIG. 1, the wafer carrier 10 is able to load twenty-five wafers, and a plurality of breathing filters 14 are positioned on the sidewalls of the wafer carrier 10. The main function of the wafer carrier 10 is conveying the wafers 12 to equipment during different processes. Since the wafers 12 have to be treated by 300 to 600 processes, the inner surfaces of the wafer carrier 10 may be polluted. Furthermore, the contaminants of the wafer carrier 10 may pollute the loaded wafers 12, which results in self-contamination. Therefore, it is necessary to sample and analyze the contaminants of the wafer carrier 10 so as to control and realize the relationship between contamination and production yield.
The prior art method of sampling contaminants of the wafer carrier 10 includes directly pouring deionized water into the wafer carrier 10. After twenty-four hours, the deionized water is drawn from the wafer carrier 10 for performing contamination analysis. However, the prior art method does not define a complete set of sampling procedure and environment, which critically affects the accuracy and certainty of sampling results.